The Norwood scale, also commonly referred to as the Norwood-Hamilton scale, is a classification system for pattern hair loss (also known as androgenic alopecia). This type of hair loss is a progressive genetic and hormonal condition that results in eventual baldness if left untreated. But before balding, people experience a variety of hair loss symptoms, including a receding hairline, hair loss at the temples, and a thinning crown.
Since androgenic alopecia symptoms tend to occur in a set pattern, hair loss classification systems are used to identify how much a man’s hair loss has progressed. The Norwood scale is currently the most common classification system used by trichologists, dermatologists, hair transplant surgeons, and other hair loss specialists.
What is the Norwood scale?
According to an article in the International Journal of Trichology, the Norwood scale for pattern hair loss was developed in 1975. But this scale was actually based on an existing scale, known as the Hamilton scale – hence why this classification system is often referred to by the full name of Norwood-Hamilton.
Hamilton originally created a scale based on the hair loss seen in over 700 different people of different ages and ethnicities. His original scale was made up of eight stages. People with Hamilton type 1,2, and 3 were considered to have hair loss but not be bald, and types 4, 5, 6, 7, and 8 were classified as types of baldness.
Hamilton’s scale was reproducible, but not perfect. For example, his ‘type 3’ was reserved for borderline cases and other types of hair loss that were difficult to classify. This is one of the reasons why Norwood decided to simplify and expand Hamilton’s scale in 1975.
The Norwood scale: Seven stages of hair loss
Norwood’s new scale reduced the amount of hair loss types from eight to seven. It also added type ‘A’ and ‘V’ variants to complement the seven stages and address the variability in hair loss that occurs from person to person. This resulted in a total of 12 possible total stages.
The Norwood scale has 12 possible stages of male pattern hair loss.
The Norwood scale’s main seven stages of pattern hair loss are:
Norwood 1: Little to no hair loss, indicative of hairline recession.
Norwood 2: Hairline recession becomes more defined.
Norwood 3: In addition to a receding hairline, there is hair loss at the temples and/or crown of the head.
Norwood 4: There is little to no hair at the very center of the crown of the head.
Norwood 5: Hair loss is present at both the front and crown, with these regions separated by a strip of hair.
Norwood 6: The band of hair separating the front and crown falls out, joining them to form one large area of hair loss.
Norwood 7: Hair loss is present across the top of the head, but the lower sides and back of the head remain unaffected.
The seven main stages of this scale aren’t too complicated. The main thing you need to know is that early stages – Norwood 1, Norwood 2, Norwood 3, and even Norwood 4 – indicate the start of pattern hair loss symptoms, like hair thinning. In contrast, later-stage hair loss – Norwood 5, Norwood 6, and Norwood 7 – imply that you have lost enough hair to be balding or that you might already be noticeably bald.
Using the Norwood scale
The Norwood scale is generally used to help someone identify how far their hair loss has progressed. This information is then used to determine their treatment options.
Identifying Norwood 1 & Norwood 2
When men first start to experience the symptoms of pattern hair loss, many of them don’t even notice it’s happening. This might sound strange, but it really isn’t too unusual, since all adults experience some minor hairline recession and hair thinning as they age.
However, if your receding is caused by androgenic alopecia, it’s crucial to try and identify symptoms early on. The sooner you start a treatment, the more likely you are to prevent hair loss and maintain healthy hair growth. And if you manage to start a hair loss treatment while you’re still in Norwood stage 2, you may not even experience the continued progression into later-stage hair loss and baldness.
Treatment options for Norwood 2, Norwood 3, and Norwood 4
People with mild-to-moderate hair loss – Norwood scale 2, 3, and 4 – are usually offered hair loss treatments. Hair loss that’s treated this early can be stopped, and in many cases, weak, thinning hair can be restored to a stronger, healthier state. According to a review in the Journal of the American Academy of Dermatology, there are three currently FDA-approved for use in men: minoxidil, finasteride, and low-level laser therapy.
Minoxidil is a topical solution or foam that’s sold in concentrations of 2 and 5 percent. This medication helps stimulate healthy hair growth by allowing more nutrients, oxygen, and blood to reach hair follicles. Minoxidil 5 percent is thought to be most effective for men.
Finasteride is an oral medication that’s meant to be taken in singular daily doses of 1-milligram. Finasteride pills target the hormonal part of androgenic alopecia. They specifically block dihydrotestosterone, the androgen that causes hair thinning and that’s thought to be one of the main causes of androgenic alopecia.
Low-level laser therapy is available in hair loss treatment clinics or can be done at home if you buy your own device. Laser hair therapy devices are FDA-cleared in a multitude of forms, including brushes, combs, headbands, and hats. The light that these devices emit is biostimulatory, encouraging hair growth and stopping the progression of pattern hair loss.
Treatment options for Norwood 5, Norwood 6, and Norwood 7
People with more extensive hair loss – Norwood scale 5, 6, or 7 – can use minoxidil, finasteride, and laser hair therapy. However, the results they achieve from these treatments may not be very good. People with such severe hair loss usually require another type of treatment – like a hair transplant.
While hair transplants can be performed from the time you reach Norwood scale 4, a study in the International Journal of Innovative Computing, Information and Control says that they’re best for men with hair loss that has reached or past Norwood scale 5. Men can choose from two main options: FUE, which stands for follicular unit extraction, and FUT, which stands for follicular unit transplantation.
FUE involves the excision of individual hair follicles from the lower scalp or body hair. FUT, in contrast, requires a small strip of skin to be removed from the back of the head and surgically sealed. Hair follicles are extracted from that strip of skin and transplanted back onto the head.
According to a study in the Hair Transplant Forum International journal, hair transplants require anything from 2,500 to 8,000 hair follicle grafts to be successful. People with Norwood scale 4 usually need 2,500 to 3,000 grafts, while those with Norwood scale 5 need 4,000 to 5,000 grafts.
Individuals who are completely or almost completely bald – Norwood scale 6 or 7 – require between 6,000 and 8,000 grafts. This requires multiple surgeries, which may involve a combination of FUE and FUT, or FUE from multiple donor sites – like the back of the head, beard, and other body parts.
Is the Norwood scale accurate?
The Norwood scale is very popular and extremely detailed. However, according to the study in the International Journal of Trichology, it isn’t very reproducible, which means it’s also not necessarily accurate.
This means that when you consult your doctor, they may tell you that your hair loss is comparable to one stage of the scale – like Norwood scale 3, for example. But if you then go and see a trichologist, hair transplant surgeon, or another specialist, they may each tell you something completely different. The surgeon may say your hair loss is at Norwood scale 2, while the trichologist may say your hair loss is closer to Norwood 4.
The lack of reproducibility in clinician ratings seems to be due to the level of detail involved in the Norwood-Hamilton scale. But obviously, adding these details was the entire reason Norwood modified the original Hamilton scale. As of yet, there haven’t been any good resolutions for this issue beyond further adaptations of Norwood’s scale or the development of completely new hair loss classification systems.
Is the Hamilton-Norwood scale still used today?
Despite the difficulties in reproducibility that the Hamilton-Norwood scale has, it’s still one of the most popular male pattern hair loss classification systems in existence. It’s also commonly used in clinical trials when developing new drugs and therapies for hair loss. While a few new systems with better reproducibility have been developed, none have come close to the popularity of the Hamilton-Norwood. Instead, researchers continue to try and create modified, simplified versions of this scale.
The Norwood-Hamilton scale was even recently adapted to assess the risk of COVID-19 infection in people with and without pattern hair loss. This study, published in the Journal of the American Academy of Dermatology, found that men with severe pattern hair loss were more likely to test positive for COVID-19 than men with Norwood 1 (no signs of hair loss).
Of course, the first thing one would assume is that the men without hair loss were simply younger. But the men without hair loss were actually the same age as those with severe hair loss. And when this study was extended to a larger group of both men and women (also published in the Journal of the American Academy of Dermatology) it found that the vast majority of COVID-19 patients had androgenic alopecia. The researchers believe that this correlation may have identified a link between the androgens involved in pattern hair loss and risk of SARS-CoV-2 infection.
Should I use the Hamilton-Norwood scale?
The Norwood scale has been around since the mid-1970s, but it’s still the most popular classification system available for androgenic alopecia. People with mild to moderate hair loss – which fall into classifications Norwood 1, 2, 3, and 4 – have the most treatment options. They can choose from FDA-approved medications like minoxidil and finasteride, and FDA-cleared devices like laser hair therapy. Men whose hair has reached Norwood scale 4 may even be able to consider hair transplantation.
Men with more extensive hair loss – Norwood scale 5 to 7 – have very limited treatment options. They are usually advised to have a hair transplant surgery like FUE or FUT. In some cases, multiple surgeries from several donor sites are required.
Pattern hair loss has the best results when it’s treated early. If you have symptoms of androgenic alopecia and have determined that your hair loss is at least a Norwood 2 on the Hamilton-Norwood scale, consider starting a hair loss treatment. If you have later-stage hair loss, you’ll likely need to consult a specialist about getting a hair transplant. But both before and after such surgeries, most people with pattern hair loss can benefit from at-home treatments like minoxidil.